Pivoting wedge expanding spinal implant and method of implanting same

ABSTRACT

A pivoting wedge expandable spinal implant. An upper portion and a lower portion are pivotally connected together. The implant, in a collapsed position, is inserted into a disc space. A driving screw engages and applies a force to a pushing portion, driving the pushing portion toward the implant&#39;s distal end. The pushing portion engages and drives a wedge toward the implant&#39;s distal end. The wedge pivots upward against an inner surface of the lower portion. The wedge continues to pivot along an inner surface of the upper portion, translating the force to the upper portion, pivoting and expanding the upper portion to an expanded position.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a spinal implant. More particularly,the invention relates to an expandable spinal implant having a pivotingwedge, configured to expand within a patient's disc space between twoadjacent vertebral bodies, from a collapsed position to an expandedposition.

Description of the Related Art

Expandable spinal implants are known in the art. Such expandableimplants can be configured to have lordotic, tapered configurations toassist in the restoration or enhancement of spinal lordosis. Theexpandability of such implants allows placement of the implant, while ina collapsed position, through a relatively small opening in a patient'sbody, into a corresponding surgically-enhanced disc space between twoadjacent vertebral bodies. Thereafter, expansion of the implant withinthe disc space increases the height between the two adjacent vertebralbodies, assisting in the restoration or enhancement of spinal lordosis.

The related art expandable implants typically have two components,pivotally held together by a pivot pin. During expansion of the implantto the expanded position, the pin, in some cases, may be incapable ofwithstanding all of the forces generated between the two components,resulting in damage to, and inoperabilty of, the implant.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an expandable spinalimplant which obviates one or more of the shortcomings of the relatedart.

It is another object of the present invention to provide a pivotingwedge expandable spinal implant for insertion into a patient's discspace between an upper vertebral body and a lower vertebral body. Theimplant has a proximal end and a distal end defining a mid-longitudinalaxis. The implant is expandable between a collapsed position and anexpanded position. The implant includes an upper portion. The upperportion has a proximal end and a distal end. The upper portion also hasan inner surface and an outer surface. The outer surface is configuredto engage a vertebral endplate of the upper vertebral body. The innersurface has an upper ramp surface.

The implant further includes a lower portion. The lower portion ispivotally engaged with the upper portion, and has a proximal end and adistal end. The proximal end includes a threaded proximal end opening.The lower portion also has an inner surface and an outer surface. Theouter surface is configured to engage a vertebral endplate of the lowervertebral body. The inner surface includes a lower ramp surface. Thelower ramp surface and the upper ramp surface define an internal pockettherebetween.

A force application device is configured to be inserted into theproximal end threaded opening. The force application device includes adistal end.

A pushing portion is defined in the proximal end of the implant. Thepushing portion has a proximal end and a distal end. The proximal end ofthe pushing portion is configured to come into contact with the distalend of the force application device.

A wedge is defined in the distal end of the implant. The wedge has aproximal end and a distal end. The proximal end of the wedge isconfigured to be in contact with the distal end of the pushing portion.The distal end of the wedge is configured to be positioned, when theimplant is in the collapsed position, within the internal pocket definedby the upper ramp surface and the lower ramp surface. The distal end ofthe wedge is further configured, when force is applied by the forceapplication device to the pushing portion, forcing the pushing portionto move in the direction of the distal end of the implant, to be moved,by the pushing portion, up along the lower ramp surface and into contactwith the upper ramp surface, translating the motion to the upper rampsurface, thereby and moving the upper ramp portion away from the lowerramp portion. The distal end of the wedge further moves up along theupper ramp surface, further expanding the implant until it reaches theexpanded position.

It is a further object of the present invention to provide a method ofinserting the expandable spinal implant as described above into apatient's disc space between an upper vertebral body and a lowervertebral body.

The method includes surgically preparing a disc space between a lowervertebral body and an upper vertebral body, inserting the implantdescribed above, in the collapsed position, into the disc space, withthe force application device applying a force to the pushing portion,thereby pushing the pushing portion toward the distal end of theimplant, pushing the wedge toward the distal end of the implant, up thelower ramp surface and into contact with at least a portion of the upperramp surface, translating the force to the upper ramp surface, movingthe upper ramp portion away from the lower ramp portion, pushing thedistal end of the wedge up the upper ramp surface, and expanding theimplant to the expanded position.

These and other objects of the present invention will be apparent fromreview of the following specification and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lower perspective view of a pivoting wedge expandable spinalimplant in accordance with the invention;

FIG. 2 is an upper perspective view of a pivoting wedge expandablespinal implant in accordance with the invention;

FIG. 3 is an exploded parts view of a pivoting wedge expandable spinalimplant in accordance with the invention;

FIG. 3A is a perspective view of an upper portion of the pivoting wedgeexpandable spinal implant in accordance with the invention, flipped overto depict an interior configuration of the upper portion, including anupper ramp portion;

FIG. 4 is a side view of a pivoting wedge expandable spinal implant inaccordance with the invention in the collapsed position;

FIG. 5 is a side cross-sectional view of a pivoting wedge expandablespinal implant in accordance with the invention in the collapsedposition;

FIG. 6 is a lower perspective view of a pivoting wedge expandable spinalimplant in accordance with the invention in the process of expanding tothe expanded position;

FIG. 7 is an upper perspective view of a pivoting wedge expandablespinal implant in accordance with the invention in the process ofexpanding to the expanded position;

FIG. 8 is a side view of a pivoting wedge expandable spinal implant inaccordance with the invention in the process of expanding to theexpanded position;

FIG. 9 is a side cross-sectional view a pivoting wedge expandable spinalimplant in accordance with the invention expanded to the 100% expandedposition;

FIG. 10 is a side cross-sectional view of a pivoting wedge expandablespinal implant in accordance with another embodiment of the invention;

FIG. 11 is a side cross-sectional view of a pivoting wedge expandablespinal implant in accordance with the invention, expanded to the 20%expanded position;

FIG. 12 is a side cross-sectional view of a pivoting wedge expandablespinal implant in accordance with the invention, expanded to the 40%expanded position;

FIG. 13 is a side cross-sectional view of a pivoting wedge expandablespinal implant in accordance with the invention, expanded to the 60%expanded position;

FIG. 14 is a side cross-sectional view of a pivoting wedge expandablespinal implant in accordance with the invention, expanded to the 80%expanded position;

FIG. 15 is a lower perspective cross-sectional view of a pivoting wedgeexpandable spinal implant in accordance with the invention, without apushing portion, and with a distal end of the force application deviceconfigured to contact a proximal end of the wedge, expanded to an 80%expanded position;

FIG. 16 is a side cross-sectional view of the pivotal wedge expandablespinal implant depicted in FIG. 15, in the collapsed position;

FIG. 17 is a lower perspective cross-sectional view of the pivotingwedge expandable spinal implant depicted in FIG. 15, expanded to a 40%expanded position;

FIG. 18 is an upper perspective view of a threaded force applicationdevice; used in the pivotal wedge expandable spinal implant depicted inFIG. 15; and

FIG. 19 is an upper perspective view of a wedge, used in the pivotalwedge expandable spinal implant depicted in FIG. 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In accordance with the invention, and as depicted in FIGS. 1-15, apivoting wedge expandable spinal implant 10 is provided, configured tobe inserted in a surgically-enhanced disc space between an uppervertebral body and a lower vertebral body (not shown). The implantincludes a proximal end 12 and a distal end 14, defining amid-longitudinal axis L-L therebetween.

In accordance with the invention, the implant includes an upper portion16. The upper portion 16 includes a proximal end 18, a distal end 20, aninner surface 22, and an outer surface 24.

In accordance with the invention, and as depicted in FIG. 2, the distalend 14 is preferably tapered, for simplicity of access to the discspace.

The outer surface 24 includes one or more raised ridges 26, for engaginga vertebral endplate of the upper vertebral body.

In accordance with the invention, and as depicted in FIGS. 3, 3A, and15, the inner surface 22 defines an upper ramp surface 28. The upperramp surface 28 extends from a first position 30 intermediate theproximal end 18 and the distal end 20, to a second position 32 proximatethe distal end 14 of the implant 10. A first planar surface 34 extendsfrom the second position 32 to the distal end 14 of the implant 10. Theupper ramp surface 28 includes an arcuate portion 36 proximate thesecond position 32. The arcuate portion 36 intersects with the firstplanar surface 34 at a first transition point 40. The invention is notlimited to the configuration of the upper ramp surface 28 describedabove. Additional configurations for the upper ramp surface 28 areconceivable and within the scope of the invention, including, but notlimited to, a substantially planar surface parallel to the longitudinalaxis.

In accordance with a preferred embodiment of the invention, the implantincludes a lower portion 46. The lower portion 46 includes a proximalend 48, a distal end 50, an inner surface 52, and an outer surface 54.The outer surface 54 includes one or more raised ridges 56, for engaginga vertebral endplate of the lower vertebral body. The inner surface 52defines a lower ramp surface 58.

In accordance with the invention, and as depicted in FIGS. 3 and 15, thelower ramp surface 58 extends from a first position 60 intermediate theproximal end 48 and the distal end 50 to a second position 62 proximatethe distal end 14 of the implant 10. A first planar surface 64 extendsfrom the second position 62 to the distal end 14 of the implant 10. Thelower ramp surface 58 includes an arcuate portion 66 proximate thesecond position 62. The arcuate portion 66 intersects with the firstplanar surface 64 at a second transition point 70. The lower portion 46further includes, at the proximal end 48, a threaded proximal aperture44. The invention is not limited to the configuration of the lower rampsurface 58 described above, and depicted in FIGS. 3, 3A and 15.Additional configurations for the lower ramp surface 58 are conceivableand within the scope of the invention, including, but not limited to, asubstantially planar surface proximate the first position 60, whichramps upward transverse to the mid-longitudinal axis, defining the rampsurface 58, to the arcuate position 66 proximate the second position 62.The lower ramp surface 58 combines with the upper ramp surface 28 todefine an internal pocket 74, internal to the implant 10.

In accordance with a preferred embodiment of the invention, and asdepicted in FIG. 4, the upper portion 16 is pivotally connected to thelower portion 46 via a hinge 76 defined at the proximal end 12 of theimplant 10.

In accordance with a preferred embodiment of the invention, a forceapplication device 80 is provided. As depicted in FIGS. 1-8, forceapplication device 80 is a screw, having a shaft 82. Shaft 82 includesthreads 84, a T-shaped distal end 86, and a distal surface 85 that isperpendicular to the mid-longitudinal axis. In the embodiment of FIG. 5,distal surface 85 includes a distal thread. The invention, however, isnot limited to use of a screw as the force application device 80, nor isthe invention limited to use of a distal thread as the distal surface85.

In accordance with one embodiment of the invention, a pushing portion 90is defined in the proximal end 12 of the implant 10. As depicted inFIGS. 5-9, pushing portion 90 includes a proximal end pocket 92. Theproximal end pocket 92 includes an opening 94 defined in the proximalend of the proximal end pocket 92. A vertical wall 96 is defined on thepushing portion 90 adjacent the proximal end pocket 92. The pushingportion 90 further includes a hook-shaped projection 98. As depicted inFIG. 5, when the implant 10 is in the collapsed position, thehook-shaped projection 98 engages a locking portion 95 on the upperportion 16 to hold the implant 10 in the collapsed position. As depictedin FIG. 8, however, when the implant 10 is being moved to the expandedposition, the force application device is moved through the proximalaperture 44. The hook-shaped projection 98 is pushed away from thelocking portion 95 to allow the implant 10 to expand. The T-shapeddistal end 86 of the force application device 80 is configured to insertthrough the opening 94, and move into the proximal end pocket 92 of thepushing portion 90, where it is held in place via a pin 93. The distalsurface 85 comes into contact with the vertical wall 96 adjacent theproximal end pocket 92, moving the pushing portion 90 towards the distalend 14 of the implant 10. The motion is then translated by the pushingportion 90, moving the pushing portion 90 toward the distal end 14 ofthe implant 10.

In accordance with another preferred embodiment of the invention, asdepicted in FIG. 8, the pushing portion 90 also includes a distal endpocket 99.

In accordance with a preferred embodiment of the invention, a wedge 100is provided proximate the distal end 14 of the implant 10. The wedge 100includes a proximal end 102 and an arcuate distal end 104. The proximalend 102 of the wedge 100 is connected to the pushing portion 90. In oneembodiment of the invention, as depicted in FIG. 5, the proximal end 102of the wedge 100 is attached to the pushing portion 90 with a pin 108.As depicted in FIG. 8, the proximal end 102 of the wedge 100 also can beconfigured to be engaged to the pushing portion 90 by contact with thedistal end pocket 99.

In accordance with another embodiment of the invention, the outersurface 24 of the upper portion 16, and the outer surface 54 of thelower portion 46 are each configured with upper and lower apertures 110,112, respectively. The upper and lower apertures 110 and 112 provideopenings to the internal pocket 74. In addition, the sides of theimplant 10 in this embodiment define side apertures 114. In thisembodiment of the invention, after the implant 10 is in place in thedisc space, bone-growth material packed into the internal pocket 74 ofthe implant 10 can grow through the respective openings 110, 112, and114. Suitable bone graft material is well-known in the art. Inparticular, the side apertures 114 allow the implant 10 to be packedwith bone graft material after the implant 10 has been inserted into thedisc space.

In accordance with a preferred embodiment of the invention, the implant10 is configured, such that, commencing in the collapsed position, asdepicted in FIG. 5, upon translation of the motion from the forceapplication device 80 to the pushing portion 90, subsequent distalmotion of the pushing portion 90 is translated to the proximal end 102of the wedge 100. As depicted in FIG. 11, the arcuate distal end 104 ofthe wedge 100 moves out of the internal pocket 74, and moves up alongthe arcuate portion 66 of the lower ramp surface 58 towards the secondtransition point 70. At this point, as depicted in FIG. 11, the implant10 is approximately 20% open. As depicted in FIGS. 11 and 12, the wedge100 moves past the first transition point 40 of the upper ramp surface28. As depicted in FIG. 12, the implant is approximately 40% open.Subsequently, as depicted in FIGS. 13 and 14, the external radius 106 ofthe arcuate distal end 104, moves along the internal upper ramp surface28. In this manner, the force applied to the pushing portion 90 by theforce application device 80 is translated into movement of the upperportion 16, thereby pivoting the upper portion 16 on hinge 76, andmoving the upper portion 16 away from, the lower portion 46. As depictedin FIG. 13, the implant 10 is approximately 60% open. As depicted inFIG. 14, the implant 10 is approximately 80% open. Movement of the upperportion 16 will continue until the implant 10 achieves the expandedposition (i.e., approximately 100% expanded, as depicted in FIG. 9).

In accordance with another embodiment of the invention, as depicted inFIG. 10, the implant 10 may include an arcuate posterior ramp portion116 defined on the pushing portion 90. As depicted in FIG. 10, theproximal end 18 of the upper portion 16 includes an arcuate portion 118.The arcuate posterior ramp portion 116 has a radius which is larger thana radius of the arcuate posterior ramp portion 118. Alternatively, theposterior ramp portions may have straight inclines, or multiple curves.Interaction between these two arcuate components further moves the upperportion 16 of the implant 10 away from the lower portion 46 of theimplant 10.

In accordance with another embodiment of the invention, as depicted inFIG. 10, the distal end 14 of the implant 10 may include distal endprojecting pins 120 projecting from the upper portion 16 and the lowerportion 46. An elastic member 122 may be wrapped around the distal endprojecting pins 120. Upon translation of the force application devicefrom the distal end of the implant, the elastic member 122 assistspulling the upper portion 16 and the lower portion 46 back together inthe collapsed position.

In accordance with a preferred embodiment of the invention, a disc spaceof a patient between an upper vertebral body and a lower vertebral bodyis surgically prepared. An implant 10, having the configuration of theinvention as described above, is inserted into the disc space, eithervia a posterior approach, or via a lateral approach. The implant 10 isinserted into the disc space in the collapsed position. The ridges 26 onthe outer surface 24 of the upper portion 16 engage a vertebral endplateof the upper vertebral body. Likewise, the ridges 56 on the outersurface 54 of the lower portion 46 engage a vertebral endplate of thelower vertebral body. As depicted in FIG. 5, the hook-shaped projection98 on the pushing portion 90 is engaged with the locking portion 95 ofthe upper portion 16, assisting in holding the upper portion 16 in placeover the lower portion 46, assisting in keeping the implant 10 in thecollapsed position.

In accordance with a preferred embodiment of the invention, the forceapplication device 80, preferably in the form of a threaded screw, ismoved in the threaded proximal aperture 44 toward the distal end 20 ofthe implant 10. The T-shaped distal end 86 is held in place in theproximal end pocket 92 by the pin 93. The distal surface 85 contacts thevertical wall 96 adjacent the proximal end pocket 92, translating motionof the force application device 80 to the pushing portion 90. Thepushing portion 90 moves toward the distal end 14 of the implant 10.This motion causes the hook-shaped projection 98 to be disengaged fromthe locking portion 95 on the upper portion 16.

In accordance with a preferred embodiment of the invention, and asdepicted in FIGS. 5-7, the motion of the pushing portion 90 issubsequently translated to the proximal end 12 of the wedge 100. Thewedge 100 moves toward the distal end 14 of the implant 10, while thepin 108 may or may not remain unloaded. The arcuate distal end 104 ofthe wedge 100 is pushed out of the internal pocket 74, and up the lowerramp surface 58, past the second transition point 70, and into contactwith the first transition point 40 on the upper portion 16. Motiontranslated to the upper portion 16, causes the upper portion 16 torotate upward on hinge 76, away from lower portion 46.

In accordance with a preferred embodiment of the invention, as the upperportion 16 commences to move the arcuate distal end 104 of the wedge 100moves along the upper ramp surface 28, moving the upper portion awayfrom the lower portion. The arcuate distal end 104 of the wedge 100continues to move up the upper ramp surface 28 until the implant 10 hasreached the expanded position.

In accordance with the invention, in the process of being expanded fromthe collapsed position to the expanded position, the wedge 100 bothpivots and engages two ramps, while the pin 108 may or may not remainunloaded. The internal pocket 74 between the upper ramp surface 28 andthe lower ramp surface 58 carries the majority of all of the forcebetween the pushing portion 90 and the components of the wedge 100. Theresulting degree of expansion in the expanded position of the implant 10is significantly increased when compared to a non-pivoting wedge. Theincreased degree of expansion of the implant 10 in the expended positionresults in an increased angle between the lower portion 46 and the upperportion 16. This increased angle results in increased lordosis betweenthe upper and lower vertebral bodies.

In accordance with another preferred embodiment of the invention, asdepicted in FIGS. 17-19, the implant 10 does not include a pushingportion 90. In this embodiment, a stem 112 of the T-shaped distal end 86of the force application device 80 fits into a notch 124 defined in theproximal end 102 of the wedge 100. With this configuration the forceapplication device 80 is positioned to translate motion directly to theproximal end 102 of the wedge 100. Rotation of the threaded forceapplication device 80 in the threaded proximal aperture 44 moves theforce application device 80 toward the distal end 14 of the implant 10.Contact between the distal surface 85 of the force application device 80with the distal end 102 of the wedge 100 translates the motion of theforce application device 80 directly to the wedge 100, thereby movingthe wedge 100 toward the distal end 14 of the implant 10. The wedge 100is moved along the lower ramp surface 58 into contact with the upperramp surface 28. The wedge 100 moves along the upper ramp surface 28,rotating the upper ramp surface 28, on the hinge 76, away from the lowerramp surface 58, until the implant 10 reaches the expanded position.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. For example, and not by way of limitation, amodular upper portion 16 can be removed, e.g., by disconnecting themodular upper portion 16 from the lower portion 46 at the hinge 76, andreplacing the removed modular upper portion with another modular upperportion 16, which may have different dimensions, in addition, all of thecomponents described above as being associated with the upper portion,and all of the components described above as being associated with thelower portion can be switched, i.e., the upper and lower portions can beentirely reversed in orientation, and the resultant implant would stillfall within the spirit and scope of the present invention. Thespecification and examples are to be considered as exemplary only, witha true scope and spirit of the invention being indicated by thefollowing claims.

We claim:
 1. An expandable spinal implant for insertion into a patient'sdisc space between an upper vertebral body and a lower vertebral body,the implant comprising: a proximal end, an opposite distal end, a lengthextending between the proximal end and the distal end, and amid-longitudinal axis extending through the proximal end and the distalend; an upper portion, the upper portion having an inner surface and anouter surface, the inner surface defining an upper surface, the uppersurface extending from a first position intermediate the distal end andthe proximal end to a second position proximate the distal end; a lowerportion, the lower portion being pivotally engaged with the upperportion, and having an inner surface and an outer surface, the innersurface defining a lower surface, the lower surface extending from afirst position intermediate the distal end and the proximal end to asecond position proximate the distal end, the lower surface including aramp portion proximate the distal end, the ramp portion extendingupwardly toward the upper portion in a direction transverse to themid-longitudinal axis, the lower surface and the upper surface definingan internal cavity therebetween; a force application device, at least aportion of the force application device being provided in the proximalend, the force application device including at least a distal surface,and being configured to alternately move the distal surface toward oraway from the distal end of the implant; a moveable portion positionedin the internal cavity, and having a proximal end portion and a distalend portion pivotally attached to one another, the proximal end portionbeing positioned to contact the distal surface of the force applicationdevice, and the distal end portion including a wedge portion beingconfigured for contact with the upper portion and for slidable movementalong the lower surface between a first position proximate the proximalend and a second position proximate the distal end, wherein movement ofthe force application device causes corresponding slidable movement ofat least the wedge portion along the lower surface, the wedge portion,as the moveable portion is moved toward the distal end, being configuredto slide upwardly on the ramp portion, pivot upwardly with respect tothe proximal end portion, and contact the upper portion to move theupper portion and the lower portion apart from one another from acollapsed position to an expanded position.
 2. The expandable spinalimplant of claim 1, wherein the outer surface of the upper portion isconfigured to engage a vertebral endplate of the upper vertebral body,and the outer surface of the lower portion is configured to engage avertebral endplate of the lower vertebral body.
 3. The expandable spinalimplant of claim 1, wherein at least one of the outer surface of theupper portion and the outer surface of the lower portion includes anaperture defined therein, to allow bone growth therethrough.
 4. Theexpandable spinal implant of claim 1, wherein the force applicationdevice comprises a threaded screw.
 5. The expandable spinal implant ofclaim 1, wherein a distal end surface of the wedge portion issubstantially arcuate, the arcuate distal end surface being configuredto contact portions of the lower surface and the upper surface.
 6. Theexpandable spinal implant of claim 1, wherein the distal end of theimplant further comprises a collapsed position return structure, thecollapsed position return structure being configured to pull the upperportion and the lower portion at the distal end in the direction of thecollapsed position upon retraction of the force application device. 7.The expandable implant of claim 1, further comprising a hook-shapedprojection positioned proximate the force application device, thehook-shaped projection being engageable with a locking portionpositioned on the upper portion, to at least temporarily hold theimplant in the collapsed position.
 8. The expandable implant of claim 1,wherein the lower portion includes an opening defined in the proximalend, the opening including an inner peripheral surface, the innerperipheral surface including at least one thread defined thereon.
 9. Theexpandable implant of claim 8, wherein the force application deviceincludes an elongated shaft, the elongated shaft including an outerperipheral surface, the outer peripheral surface including at least onethread defined thereon, the at least one thread on the outer peripheralsurface of the shaft being configured to engage the at least one threadon the inner peripheral surface of the opening.
 10. The expandableimplant of claim 1, wherein the upper surface includes a substantiallyflat surface.
 11. The expandable implant of claim 1, further comprisinga pin for pinning the proximal end portion and the distal end portion toone another to facilitate pivotal attachment thereof.
 12. An expandablespinal implant for insertion into a patient's disc space between anupper vertebral body and a lower vertebral body, the implant comprising:a proximal end, an opposite distal end, a length extending between theproximal end and the distal end, and a mid-longitudinal axis extendingthrough the proximal end and the distal end; an upper portion, the upperportion having an inner surface and an outer surface, the outer surfacebeing configured to engage a vertebral endplate of the upper vertebralbody, the inner surface defining an upper surface, the upper surfaceextending from a first position intermediate the distal end and theproximal end to a second position proximate the distal end; a lowerportion, the lower portion being pivotally engaged with the upperportion, and having an inner surface, and an outer surface, the outersurface being configured to engage a vertebral endplate of the lowervertebral body, the inner surface defining a lower surface, the lowersurface extending from a first position intermediate the distal end andthe proximal end to a second position proximate the distal end, thelower surface including a ramp portion proximate the distal end, theramp portion extending upwardly toward the upper portion in a directiontransverse to the mid-longitudinal axis, the lower surface and the uppersurface defining an internal cavity therebetween; a force applicationdevice having a distal end surface and being alternately moveable towardor away from the distal end of the implant via actuation of the forceapplication device; and a moveable portion positioned in the internalcavity, and having a proximal end portion and a distal end portionpivotally attached to one another, the proximal end portion beingpositioned to contact the distal end surface of the force applicationdevice, and the distal end portion including a wedge portion beingconfigured for contact with the upper portion and for slidable movementalong the lower surface, wherein movement of the force applicationdevice causes corresponding slidable movement of at least the wedgeportion along the lower surface, the wedge portion, as the moveableportion is moved toward the distal end, being configured to slideupwardly on the ramp portion, pivot upwardly with respect to theproximal end portion, and contact the upper portion to move the upperportion away from the lower portion, and move the implant from acollapsed position to an expanded position.
 13. The expandable spinalimplant of claim 12, wherein at least one of the outer surface of theupper portion and the outer surface of the lower portion includes anaperture defined therein, to allow bone growth therethrough.
 14. Theexpandable spinal implant of claim 12, wherein a distal end surface ofthe wedge portion is substantially arcuate, the arcuate distal endsurface being configured to contact portions of the lower surface andthe upper surface.
 15. The expandable implant of claim 12, furthercomprising a hook-shaped projection positioned proximate the forceapplication device, the hook-shaped projection being engageable with alocking portion positioned on the upper portion, to at least temporarilyhold the implant in the collapsed position.
 16. The expandable implantof claim 12, wherein the lower portion includes an opening defined inthe proximal end, the opening including an inner peripheral surface, theinner peripheral surface including at least one thread defined thereon.17. The expandable implant of claim 16, wherein the force applicationdevice includes an elongated shaft, the elongated shaft including anouter peripheral surface, the outer peripheral surface including atleast one thread defined thereon, the at least one thread on the outerperipheral surface of the shaft being configured to engage the at leastone thread on the inner peripheral surface of the opening.
 18. Theexpandable implant of claim 12, further comprising a pin for pinning theproximal end portion and the distal end portion to one another tofacilitate pivotal attachment thereof.
 19. An expandable spinal implantfor insertion into a patient's disc space between an upper vertebralbody and a lower vertebral body, the implant comprising: a proximal end,an opposite distal end, a length extending between the proximal end andthe distal end, and a mid-longitudinal axis extending through theproximal end and the distal end; an upper portion, the upper portionhaving an inner surface and an outer surface, the inner surface definingan upper surface, the upper surface extending from a first positionintermediate the distal end and the proximal end to a second positionproximate the distal end; a lower portion, the lower portion beingpivotally engaged with the upper portion, and having an inner surfaceand an outer surface, the inner surface defining a lower surface, thelower surface extending from a first position intermediate the distalend and the proximal end to a second position proximate the distal end,the lower surface including a ramp portion proximate the distal end, theramp portion extending upwardly toward the upper portion in a directiontransverse to the mid-longitudinal axis, the lower surface and the uppersurface defining an internal cavity therebetween; a force applicationdevice, at least a portion of the force application device beingprovided in the proximal end, the force application device including atleast a distal surface, and being configured to alternately move thedistal surface toward or away from the distal end of the implant viaactuation thereof; a moveable portion positioned in the internal cavity,and having a proximal end portion and a distal end portion pivotallyattached to one another, the proximal end portion being positioned tocontact the distal surface of the force application device, and thedistal end portion including a wedge portion being configured forslidable movement along the lower surface between a first position and asecond position, the first position being closer to the proximate endthan the second position, wherein movement of the force applicationdevice causes corresponding slidable movement of at least the wedgeportion along the lower surface, the wedge portion, as the moveableportion is moved toward the distal end, being configured to slideupwardly on the ramp portion, pivot upwardly with respect to theproximal end portion, and contact the upper portion to move the upperportion and the lower portion apart from one another from a collapsedposition to an expanded position.
 20. The expandable implant of claim19, wherein the lower portion includes an opening defined in theproximal end, the opening including an inner peripheral surface, theinner peripheral surface including at least one thread defined thereon,and wherein the force application device includes an elongated shaft,the elongated shaft including an outer peripheral surface, the outerperipheral surface including at least one thread defined thereon, the atleast one thread on the outer peripheral surface of the shaft beingconfigured to engage the at least one thread on the inner peripheralsurface of the opening.